kern/55315: ntpd stepping completely breaks time

[martin%NetBSD.org@localhost]

>Number:         55315
>Category:       kern
>Synopsis:       ntpd stepping completely breaks time
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu May 28 18:40:00 +0000 2020
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.64
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD thirdstage.duskware.de 9.99.64 NetBSD 9.99.64 (MODULAR) #346: Thu Oct 9 07:17:40 CEST 2070 martin%thirdstage.duskware.de@localhost:/usr/src/sys/arch/sparc64/compile/MODULAR sparc64
Architecture: sparc64
Machine: sparc64
>Description:

Not sure if this is a kernel bug (the recent kern_tc.c changes?) or new ntpd,
but currently on this machine time keeping is impossible with ntp:

[/tmp] root@thirdstage # date
Thu May 28 20:14:27 CEST 2020
[/tmp] root@thirdstage # /etc/rc.d/ntpd onestart
Starting ntpd.
[/tmp] root@thirdstage # date
Thu May 28 20:14:36 CEST 2020
[/tmp] root@thirdstage # date
Thu May 28 20:19:16 CEST 2020
[/tmp] root@thirdstage # date
Fri Feb 21 19:29:10 CET 2121

ntpq shows a big offset:

[~] martin@thirdstage > ntpq -pn
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 91.199.88.144   131.188.3.222    2 u  411   64  100   24.378  +14126.   0.002

untill it steps:

[~] martin@thirdstage > ntpq -pn
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 91.199.88.144   .STEP.          16 u    -   64    0    0.000   +0.000   0.002

and then we are far far in the future:

[/tmp] root@thirdstage # date
Fri Feb 21 19:29:10 CET 2121

Interestingly ntpdate brings us back:

[/tmp] root@thirdstage # ntpdate 91.199.88.144
28 May 20:31:02 ntpdate[510]: step time server 91.199.88.144 offset +1116052095.999830 sec
[/tmp] root@thirdstage # date
Thu May 28 20:31:03 CEST 2020


w/o ntpd running, time seems to progress as it should.

>How-To-Repeat:
s/a

>Fix:
n/a